It can be downloaded for FREE. It's compatible with iPhone, iPod Touch and iPad (requires iOS 3.0 or later). Beside all standard Todoist's features, Todoist for iOS also includes OFFLINE SYNC.

We will soon release the Android version as well and will notify you once it's been published.

Thank you for your patience and continued support, we hope this App will increase your productivity and provide a great extension for Todoist's functionality which we will continue to develop according to your suggestions and feature requests posted in our Votebox: http://todoist.com/Vote/